Rear bumper for an automobile



FIG. 1 is a left front perspective view of a rear bumper for an automobile showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a right side elevational view thereof.

The broken lines illustrate environmental structure only and form no part of the claimed design. 

CLAIM The ornamental design for a rear bumper for an automobile, as shown and described. 